1. Field of the Invention
An aspect of the present invention relates to an optical recording and/or reproducing apparatus to record and playback data of an optical disc, and, more particularly, to an interface device of an optical recording and/or reproducing apparatus wherein the configuration of an interface circuit between a pickup that reads and writes information from/on an optical disc and a radio frequency (RF) integrated circuit (IC) for signal processing is simplified.
2. Description of the Related Art
With advances in video and audio media technologies, a recording medium in which high quality video and audio data may be recorded and stored for a lengthy period of time, for example an optical disc like a digital versatile disc (DVD), has been developed and made commercially available. Along with this medium, an optical recording and/or reproducing apparatus which may record and/or reproduce video and audio data on the optical disc, for example, a DVD player, has also been developed and made commercially available.
This optical recording and/or reproducing apparatus reproduces video and/or audio data recorded on the optical disc and outputs the reproduced data via a screen and/or a speaker. The optical recording and/or reproducing apparatus has various advantages over a conventional video and/or audio reproducing apparatus in terms of higher-quality video and/or audio signal reproduction due to a higher signal-to-noise ratio, a lower noise level due to regularities in reproduction and modulation, minimal signal distortion, ghost-free reproduction, and a random access capability. Thus, the optical recording and/or reproducing apparatus has been in a trend towards rapid advances and widespread use.
Various types of optical recording and/or reproducing apparatuses, such as a compact disc player (CDP), a laser disc player (LDP), a compact disc graphic player (CDGP), and a video compact disc player (VCDP), have been developed and used extensively. Recently, DVDs have been developed using moving picture compression techniques such as moving picture experts group 2 (MPEG2), moving picture experts group 4 (MPEG4), and Digital Video EXpress (DivX). A blu-ray disc (BD) and a high definition-DVD (HD-DVD) have also been developed using a blue laser technology. Along with these, DVD players have been developed to record and playback corresponding discs.
As shown in FIG. 1, such an optical recording and/or reproducing apparatus uses a laser diode (LD) which generates a laser signal to read and write information from/on a disc 12, a BD, HD-DVD, DVD, or CD. The LD has input/output characteristics which vary relatively very sensitively with the operating temperature thereof.
That is, the LD requires a different input (typically expressed in an electric current value) depending upon the operating temperature thereof to output a laser signal of a constant power level irrespective of the operating temperature thereof. Thus, there is a need for an Auto laser diode Power Control (APC) technique to optimally control the LD. This APC technique determines the performance of the optical recording and/or reproducing apparatus.
An APC unit 22 using such an APC technique is provided to feed a variation in the output of the LD back to the LD to keep the output of the LD constant. Generally, the APC unit 22 is provided in a radio frequency (RF) integrated circuit (IC) 20 together with an RF signal processor 24. The RF IC 20 is placed on a main printed circuit board (PCB) 30.
On the other hand, an LD driver 14 is provided in a pickup 10 to drive the LD. Thus, the pickup 10 and the main PCB 30 are interconnected via connectors 40 to constitute an interface circuit between the LD driver 14 and the RF IC 20.
As a result, the RF IC 20 has to receive a monitor signal corresponding to an output variation of a monitor photo diode (MPD) attached to the LD through the connectors 40. The LD driver 14 also has to receive a control signal from the RF IC 20 through the connectors 40.
For this reason, where the optical recording and/or reproducing apparatus of FIG. 1 is a universal optical recording and/or reproducing apparatus that is capable of recording and playing back all kinds of discs 12 including a BD, HD-DVD, DVD, and CD, a plurality of LD drivers 14 must be separately provided corresponding respectively to a plurality of LDs configured for recording/playback of the respective discs 12, and have separate outputs corresponding respectively to the LDs. This increases the number of input/output pins of the pickup 10 and RF IC 20 on the main PCB 30, thus making the layout of the PCB and the structures of the connectors 40 complicated, resulting in degradation in signal quality.
Moreover, because a multiplexer (MUX) 26 is provided in the RF IC 20 to multiplex input/output signals of the pickup 10 and RF IC 20, the number of pins of the connectors 40 from the pickup 10 to the RF IC 20 on the main PCB 30 increases, which leads to an obstacle that prevents smallness, lightness, and cost effectiveness of the optical recording and/or reproducing apparatus.